The present invention relates to a method for inputting reference printed circuit board data to an apparatus for automatic inspection of printed circuit board assemblies which checks such printed circuit board assemblies for any omissions or mis-placements of component parts by processing a picture image thereof, and more particularly relates to such a method for inputting reference printed circuit board assembly data to such an automatic inspection apparatus, wherein such data are inputted from a reference or sample printed circuit board assembly rather than piecemeal as individual data, i.e. are inputted by example rather than directly.
In the prior art, there have been proposed various types of method for inputting reference printed circuit board assembly data to such an automatic printed circuit board assembly inspection machine. That is to say, when an automatic printed circuit board component mounting machine is used for mounting various component parts such as micro chips, other semiconductor devices, resistors, capacitors, and the like to an empty or bare printed circuit board in order to prepare a printed circuit board assembly ready for suffering a soldering process, it is possible that in an individual instance not all the component parts will be properly assembled to the bare printed circuit board according to the required arrangement therefore. Therefore an inspection or checking process is required to be performed for verifying that all the component parts are properly assembled to the bare printed circuit board, after such an automatic printed circuit board component mounting machine has completed its job of thus mounting the various component parts to said bare printed circuit board, so as to ensure that all of the components are indeed mounted to the bare printed circuit board at correct positions thereon and in their correct orientations, and for verifying that there is no omission of any such component parts. And, if such an inspection process is conducted manually by a human operator, it is not possible to completely eliminate the possibility of error, and further the speed of inspection is necessarily slow, thus hindering productivity and raising final cost of the assembly. Accordingly, lately, various types of automatic printed circuit board assembly inspection machine have been proposed for performing such an inspection process automatically. Such an automatic printed circuit board assembly inspection machine of course requires, before it can perform and fulfill its inspection function, data to be inputted to it for specifying the correct numbers, types, positions, and orientations of the parts to be fitted to a bare printed circuit board to constitute the printed circuit board assembly which said automatic printed circuit board assembly inspection machine is intended to inspect (such data will hereinafter in this specification be termed reference printed circuit board assembly data), as well as requiring input of the basic parameters of the bare printed circuit board itself.
Now, an exemplary such prior art automatic printed circuit board assembly inspection machine, and the method of inputting reference printed circuit board assembly data thereto and the method of subsequent operation of said automatic printed circuit board assembly inspection machine, will be explained with regard to FIGS. 7 through 9 of the appended drawings.
In FIG. 7, there is shown an automatic printed circuit board assembly inspection machine according to the prior art, which comprises: a TV camera 3 for forming an image of a subject printed circuit board assembly 2--2; a storage unit 4 for storing reference printed circuit board data which are inputted from a keyboard 8, or in other words the specification of the correct numbers, types, positions, and orientations of the component parts (schematically denoted by the reference symbols 1) to be fitted to empty printed circuit boards 7 to constitute the printed circuit board assemblies 2--2 which are required to be checked and inspected (the so called "subject " printed circuit board assemblies), as well as basic data relating to the type subject printed circuit board assemblies 2--2 which are to be processed and also data relating to the inspection procedure which is to be employed; a determination circuit 5 for comparing the data stored in the storage unit 4 with the data which are indicated by the picture transmitted by the TV camera 3 and for determining whether or not agreement exists therebetween, in other words whether or not all the parts 1 are indeed correctly fitted to the subject printed circuit board assembly 2--2 in the appropriate positions and orientations; and a display unit 6 for displaying the results of the determination thus made by the determination circuit 5.
Thus, before inspecting any subject printed circuit board assemblies 2--2, it is required to input data into the storage unit 4 for specifying the correct numbers, types, positions, and orientations of the component parts 1 to be fitted to a empty printed circuit board 7 for making up such a subject printed circuit board assembly 2--2, for specifying the type of base printed circuit board 7 itself, and for specifying parameters of the inspection procedure. This so called reference printed circuit board data is inputted via the keyboard 8 in a so called teaching process, by following a schematic flow chart such as shown exemplarily in FIG. 9. This teaching process is performed while making reference to a reference printed circuit board assembly such as the reference printed circuit board assembly 2--1 exemplarily shown in FIG. 8 which consists of a bare printed circuit board 7 with the appropriate components 1 fitted thereto in the appropriate positions and orientations, said reference printed circuit board assembly 2--1 thus being intended to serve as a model for all the subject printed circuit board assemblies 2--2 which are to be inspected and checked. This teaching process routine will now be explained, with reference to FIG. 9.
First, in the first step ST1 of the FIG. 9 flow chart, the card number of the bare printed circuit board 7 of this reference printed circuit board assembly 2--1 is inputted to the storage unit 4 via the keyboard 8, and then the flow of control passes next to the step ST2.
In this next step ST2, numerical data relating to the correct type, position, and orientation of a one of the component parts 1 to be fitted to the empty printed circuit board 7 for making up the subject printed circuit board assembly 2--2 is inputted from the keyboard 8, as well as information on the characteristics of such a component part such as the color, the brightness, and so thereof; and then the flow of control passes next to the decision step ST3.
In this decision step ST3, a decision is made as to whether or not all of the data relating to all of the component parts 1 to be fitted to the empty printed circuit board 7 for making up the subject printed circuit board assembly 2--2 has yet been inputted. If the result of this decision is YES, so that all required data has now been inputted and is now available, then the flow of control passes next to the step ST4; but, if the result of this decision is NO, so that further data remains to be inputted, then the flow of control passes next to the step ST2 again, to cycle around once more and to input further data via the keyboard 8.
In the step ST4, at which point the input of all the required data has been completed, then the inputted numerical data are all stored in the storage unit 4, to constitute reference data relating to the reference printed circuit board assembly 2--1, and then the flow of control passes next to exit this teaching routine, without doing anything further.
Next, the process of inspection of a subject printed circuit board assembly 2--2 such as the one exemplarily shown in FIG. 7 will be described. When such a subject printed circuit board assembly 2--2 is presented for inspection, the determination circuit 5 compares the numerical data obtained from the picture image of said subject printed circuit board assembly 2--2 produced by the TV camera 3 with the numerical data outputted from the storage unit 4, and the results of this comparison are shown on the display unit 6. Thus, if any one of the component parts 1 which should be present on said subject printed circuit board assembly 2--2 is in fact missing or improperly positioned or is mis-aligned or is mis-oriented, there will be a disagreement between said numerical data obtained from the picture image of said subject printed circuit board assembly 2--2 produced by the TV camera 3 and said numerical data outputted from the storage unit 4, and this disagreement will be detected by the determination circuit 5 and will be signalized upon the display unit 6, along with an indication of the nature of the discrepancy, i.e. along with an indication of which part is missing, is misplaced, is mis-aligned, or is mis-oriented.
With such a method for inputting reference printed circuit board data, when an attempt is made to increase the precision of inspection by increasing the number of numerical data which serve as reference data for the inspection process, the number of such reference data that are required to be inputted from the keyboard 8 during the teaching process of FIG. 9 becomes greater and greater, and this makes the time and labor for inputting such reference data excessive. Thus, this can lead to inefficiency and delays in production, and further the possibility of error is increased beyond an acceptable level.